Process for the production of tropic acid



Patented Dec. 4, 1945 UNITED STATES PATENT OFFICE PROCESS FOR THE PRODUCTION OF TROPIC ACID Meyer Sletzinger, Bronx, N; Y., and Grover C. Paulsen, Jr., Harrisonburg, Va., assignors to Merck & 00., Inc., Railway, N. 1., a corporation of New Jersey No Drawing. Application April 30, 1943,

Serial No. 485,152

8 Glaims.

This invention relates to an improved process for the production of d'-1-tropic acid, and esters thereof.

Tropic acid,

CHIOH retains almost half of the starting material, which is not reduced, and cannot be removed from the residue.

It has also been proposed to catalytically reduce a purified phenyl-a-hydroxymethylene acetic acid ester in the presence of palladium catalyst, but this process gives 'an impure product, with poor yields.

' We have now discovered that tropic acid may be produced in quantitative yields by a simple economical process.

According to our invention, a lower alkyl ester of phenyl-a-hydroxymethylene acetic acid is catalytically reduced in the presence of Raney nickel. The reduction product may be hydrolyzed, as for example. in aqueous barium hydroxide. solution, and tropic acid recovered.

The reaction may be illustrated as follows, in terms of the ethyl ester:

COOCsHl cane-0000.11. H:

(MHz-CH C HOE Raney nickel CHaOH plienyl-u-hydro meth lene aceto tro lc acid eth lester aci ethyl ester p y COOH hydrolysis CuHu-CH CHzOH Also, we have discovered, within the scope of crude phenyl-a-hydroxymethylene acetic acid ester may be used as starting material, instead of a purified form as previously thought necessary. Such purification involved a distillation step in which about 30% of the phenyl-a-hydroxy methylene acetic acid was decomposed.

The following example illustrates a method of carrying out the present invention, but it is to be understood that this example is given by way of illustration and not of limitation.

' Example 8.1 gms. of phenyl-a-hydroxymethylene acetic acid ethyl ester are dissolved in cc. of absolute ethanol. Raney nickel is added to the solution, which is then hydrogenated until the required amount of hydrogen is absorbed. The catalyst is filtered, and the solvent removed by evaporation. The hydrogenated product (an oil) is hydrolyzed in aqueous barium hydroxide solution, acidified, extracted with ether, dried over sodium sulfate, and the ether evaporated. The remaining oil crystallizes. Benzene is added, and the material filtered. Tropic acid of melting point 117 C. is obtained in quantitative yield.

Instead of the ethyl ester of phenyl-a-hydroxymethylene acetic acid exemplified as starting material in the foregoing specific illustration of our invention, other lower alkyl esters of theacid may be employed, as for instance, the methyl, propyl, butyl esters, etc.

Modifications may be made in carrying out the present invention, without departing from the spirit and scope thereof, and we are to be limited only by the appended claims.

We claim:

1. Process comprising hydrogenating a lower alkyl ester of phenyl-a-hydroxymethylene acetic acid in the presence of Raney nickel.

- 2. Process comprising hydrogenating phenyla-hydroxymethylene acetic acid ethyl ester in the presence of Raney nickel.

3. Process comprising hydrogenating a lower alkyl ester of phenyl-a-hydroxymethylene acetic acid in the presence of Raney nickel, and recovering an ester of tropic acid.

4. Process comprising hydrogenating a lowe alkyl ester of phenyl-a-hydroxymethylene acetic acid in the Presence of Raney nickel, and recovering tropic acid.

2 i v v 2,890,278

5. Process comprising hydrogenating phenyl-a- I hydroxymethylene acetic acid ethyl ester in the presence or Raney nickel, and recovering the ethyl ester oi tropic acid.

6. Process comprising hydrogenating phenyl-ehydroxymethyiene acetic acid ethyl ester in the presence of Haney nickel, and recovering tropic acid. i

7. Process comprising hydrogenating a lower alkyl ester of phenyl-a-hydroxymethylene acetic acid in the presence of Raney nickel, hydroiyzing the reduction product, and recovering tropic acid.

8. Process comprising hydrogenating phenyl-ehydroxymethylene acetic acid ethyl ester in the presence oi. Raney nickel, hydroiyzing the reduction product, and recovering tropic acid.

MEYER SLE'I'ZINGER.

GROVER C. PAULBEN, JR. 

